1. Field of the Invention
The present invention relates to feeding tubes used to deliver nutrition, fluids and medicine directly into the gastro-intestinal tract of patients unable to be fed normally. The present invention further relates to tubes used to aspirate fluid and air from a patient""s gastro-intestinal tract. More specifically, this invention concerns a single lumen tube for use in both delivering nutrition, fluid, returned aspirate, and medication to the gastro-intestinal tract as well as aspirating air and excess fluid from the gastro-intestinal tract.
2. Description of the Prior Art
Frequently, hospital patients are unable to consume food normally. In these situations, it is often necessary to use a feeding tube to provide nutrition, fluids, and/or medicine. Such a tube is inserted into a patient""s gastro-intestinal tract through the nose (nasogastric or nasoenteric tubes) or surgically by means of a gastrostomy or jejunostomy. Because adequate nutritional intake facilitates recovery, the proper use of a feeding tube can greatly benefit a patient. However, feeding tubes also pose some discomfort, and even some potential threats, to patients.
A number of commercially available feeding tubes exist. Unfortunately, all presently available feeding tubes suffer from a variety of deficiencies. One common problem is that a feeding tube may deliver the fluids (which include liquid nutrition, hydrating fluids, medicine and previously aspirated materials being returned to the patient) at a rate exceeding the ability of the gastro-intestinal tract to absorb said fluids. This results in an accumulation of fluid within the intestine. In particularly bad cases, accumulation of fluid causes distension of the intestine that leads to the temporary loss of all residual intestinal function. In rare cases, this intestinal distention may induce fatal vagal reflex circulatory changes. Severely ill, malnourished patients are most at risk for developing the complications of overfeeding and also most in need of the earliest optimum nutrition.
A patient""s impaired digestive system may also produce too many digestive secretions for the patient to reabsorb immediately. A typical person secretes seven to eight liters of fluid per day, starting with saliva. All secretions normally are reabsorbed by the intestine, without net loss or gain of fluid for the body. Unfortunately, during recovery from surgery the level of secretions remains relatively constant, while the intestine""s ability to absorb secretions typically is impaired, sometimes severely. The result can be a build up of fluid in the intestine, with the same detrimental side effects as found with over-feeding.
The problem of digestive secretions can be exacerbated by feeding. When concentrated nutrition is delivered to a patient""s gastro-intestinal tract, the body""s natural response is to produce digestive secretions to dilute the feedings and break down the complex nutrients for absorption by the intestine. However, if a patient""s gastro-intestinal function is severely impaired only a portion of the total fluid may be absorbed. By way of example, for 2 ml of nutrition delivered to the gastro-intestinal tract, 10 ml of digestive secretions may be provided in response. The intestine temporarily may be capable of absorbing only 2 ml of fluid, resulting in a net increase of 10 ml to the volume of fluid in the gastro-intestinal tract. This scenario may be repeated as feedings continue, causing progressive intestinal distension which, in turn, further impairs intestinal function.
To avoid problems of overfeeding or excessive secretion build up during recovery, a patient""s gastro-intestinal tract may be aspirated to remove excessive fluid. However, any secretions removed in this way must be measured and recorded. An equal volume of fluid must be returned to the body, usually intravenously, to avoid a net loss of fluids and dehydration of the patient.
The very presence of a nasal feeding tube stimulates swallowing by the patient, introducing additional air into the intestine. The presence of air within the gastro-intestinal tract interferes with the propulsion and absorption of nutrition and can be quite uncomfortable or painful to a patient. The use of an aspirating tube to remove air from the gastro-intestinal tract has been used to combat this problem.
Unfortunately, the use of a second tube for aspiration presents new problems. The introduction of a second tube only adds to the pain and discomfort experienced by a patient. Furthermore, if a separate second tube is used, it may be difficult to effectively locate it proximate to the feeding tube, thereby preventing it from aspirating excessive food present in the intestine. Attempts have been made to overcome the difficulties of feeding and aspirating with two separate tubes by combining them into a single construction with two lumens. Such structures are of necessity larger than a single lumen system. Placing two lumens in a single structure also decreases the flexibility of the structure, resulting in increased tissue trauma and discomfort to a patient. Fabricating a double lumen structure also presents increased production difficulties and costs.
The need exists, therefore, for a single lumen feeding tube capable of both delivering nutrition to the intestine as well as aspirating to remove excessive food, secretions, or air from the intestine. Such a tube should allow nutrition to be delivered to a patient""s gastro-intestinal tract more distally, while further allowing the prompt removal of more proximal excessive fluids to avoid intestinal distension. Such a feeding tube should ideally be of a size and resilience to avoid undue discomfort to the patient, while still effectively performing nutritional delivery and aspiration. Furthermore, a tube is needed that allows for the duration and frequency of cyclical nutrition delivery to, and aspiration from, the gastro-intestinal tract to provide optimal absorption of nutrition while preventing an excessive accumulation of fluids.
The present invention comprises a single lumen feeding tube of delivering nutrition as well as performing aspiration of the intestine. The feeding tube includes a one way valve, which may comprise a flattened tip at its distal end, and a plurality of aspiration pores proximate to the feeding tip. While nutrition is being delivered through the feeding tube, the feeding tip remains open and delivers most of the nutrition more distally into the intestine. Whenever suction is applied to the feeding tube, the flattened feeding tip closes, allowing more proximal aspiration to occur only via the plurality of pores located proximate to the feeding tip.